Organic light emitting display and method of fabricating the same

ABSTRACT

Disclosed are an organic light emitting display and a method of fabricating the same that are capable of preventing deterioration of adhesive strength of a glass frit for sealing a substrate. An organic light emitting device according to one embodiment of the present invention includes a first substrate including a pixel region and a non-pixel region, an array of organic light emitting pixels formed over the pixel region of the first substrate, and a second substrate placed over the first substrate, the array being interposed between the first and second substrates. The organic light emitting device of this embodiment further includes an electrically conductive line formed over the non-pixel region of the first substrate, and a frit seal interposed between the first and second substrates and surrounding the array such that the array is encapsulated by the first substrate, the second substrate and the frit seal, wherein the electrically conductive line comprises a portion overlapping the frit seal in a segment of the device such that the portion of the electrically conductive line substantially eclipses the frit seal when viewed from the first substrate.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to and the benefit of Korean PatentApplication Nos. 10-2006-0007962, filed Jan. 25, 2006, and10-2006-0027321, filed Mar. 27, 2006, the disclosures of which areincorporated herein by reference in their entirety. This application isrelated to and incorporates herein by reference the entire contents ofthe following concurrently filed applications:

Application Title Atty. Docket No. Filing Date No. ORGANICLIGHT-EMITTING DISPLAY SDISHN.043AUS DEVICE AND METHOD OF FABRICATINGTHE SAME ORGANIC LIGHT-EMITTING DISPLAY SDISHN.045AUS DEVICE AND METHODOF MANUFACTURING THE SAME ORGANIC LIGHT EMITTING DISPLAY SDISHN.048AUSDEVICE ORGANIC LIGHT-EMITTING DISPLAY SDISHN.051AUS DEVICE WITH FRITSEAL AND REINFORCING STRUCTURE ORGANIC LIGHT EMITTING DISPLAYSDISHN.052AUS DEVICE METHOD OF FABRICATING THE SAME ORGANIC LIGHTEMITTING DISPLAY SDISHN.053AUS AND METHOD OF FABRICATING THE SAMEORGANIC LIGHT-EMITTING DISPLAY SDISHN.054AUS DEVICE WITH FRIT SEAL ANDREINFORCING STRUCTURE BONDED TO FRAME METHOD FOR PACKAGING ORGANICSDISHN.055AUS LIGHT EMITTING DISPLAY WITH FRIT SEAL AND REINFORCINGSTURUTURE METHOD FOR PACKAGING ORGANIC SDISHN.056AUS LIGHT EMITTINGDISPLAY WITH FRIT SEAL AND REINFORCING STURUTURE ORGANIC LIGHT-EMITTINGDISPLAY SDISHN.060AUS DEVICE AND THE PREPARATION METHOD OF THE SAMEORGANIC LIGHT EMITTING DISPLAY SDISHN.061AUS AND FABRICATING METHOD OFTHE SAME ORGANIC LIGHT-EMITTING DISPLAY SDISHN.062AUS AND METHOD OFMAKING THE SAME ORGANIC LIGHT EMITTING DISPLAY SDISHN.063AUS ANDFABRICATING METHOD OF THE SAME ORGANIC LIGHT EMITTING DISPLAYSDISHN.064AUS DEVICE AND MANUFACTURING METHOD THEREOF ORGANICLIGHT-EMITTING DISPLAY SDISHN.066AUS DEVICE AND MANUFACTURING METHOD OFTHE SAME ORGANIC LIGHT EMITTING DISPLAY SDISHN.067AUS AND FABRICATINGMETHOD OF THE SAME ORGANIC LIGHT EMITTING DISPLAY SDISW.017AUS ANDMETHOD OF FABRICATING THE SAME ORGANIC LIGHT EMITTING DISPLAYSDISW.018AUS DEVICE METHOD OF FABRICATING THE SAME

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to organic light emitting display devices.More particularly, the present invention relates to packaging organiclight emitting display devices.

2. Description of the Related Art

With the goal of improving upon the shortcomings of conventionaldisplays such as cathode ray tubes, attention has recently been focusedon flat panel displays such as liquid crystal displays, organic lightemitting displays, plasma display panels (PDP), and so on.

Since the liquid crystal display is a passive device rather than anemissive device, it is difficult to make having high brightness andcontrast, a wide viewing angle, and a large-sized screen. While the PDPis an emissive device, it is heavy, consumes much power, and requires acomplex manufacturing process, compared to other displays.

Meanwhile, since the organic light emitting display (OLED) is anemissive device, it has a wide viewing angle, and high contrast. Inaddition, since it does not require a backlight, it can be madelightweight, compact, and power efficient. Further, the OLED can bedriven at a low DC voltage, has a rapid response speed, and is formedentirely of solid material. As a result, the OLED has the ability towithstand external impact and a wide range of temperatures, and can befabricated by a simple method at low cost.

The discussion of this section is to provide a general background oforganic light-emitting devices and does not constitute an admission ofprior art.

SUMMARY OF CERTAIN INVENTIVE ASPECTS

One aspect of the invention provides an organic light emitting device.This device includes a first substrate comprising a pixel region and anon-pixel region, an array of organic light emitting pixels formed overthe pixel region of the first substrate, and a second substrate placedover the first substrate, the array being interposed between the firstand second substrate. The device further includes an electricallyconductive line formed over the non-pixel region of the first substrate,and a frit seal interposed between the first and second substrates andsurrounding the array such that the array is encapsulated by the firstsubstrate, the second substrate and the frit seal, wherein theelectrically conductive line comprises a portion overlapping the fritseal in a segment of the device such that the portion of theelectrically conductive line substantially eclipses the frit seal whenviewed from the first substrate.

In the above-described device, the portion of the electricallyconductive line may substantially totally eclipse the frit seal whenviewed from the first substrate. The frit seal may contact theelectrically conductive line. There may be substantially no organicmaterial between the frit seal and the electrically conductive line. Thedevice may further comprise at least one layer located between theelectrically conductive line and the first substrate, the at least onelayer comprising an organic material. The electrically conductivematerial may further comprise a portion that does not overlap the fritseal. The electrically conductive line may extend along a peripheraledge of the first substrate, and wherein the frit seal extends along theperipheral edge of the first edge. The electrically conductive line maybe made of metal. In another segment of the device, the frit seal mayfurther comprise a non-eclipsed portion that is not eclipsed by theelectrically conductive line when viewed from the first substrate.

Still referring to the above described device, the frit seal may have awidth taken in a cross-sectional plane, and the electrically conductiveline may have a width taken in the cross-sectional plane, and whereinthe width of the frit seal is substantially smaller than the width ofthe electrically conductive line. The electrically conductive line maycomprise a power supply line electrically connected to the array. Theelectrically conductive line may comprise a portion overlapping the fritseal in substantially throughout the device such that the portion of theelectrically conductive line substantially eclipses the frit seal whenviewed from the first substrate.

Yet still referring to the above described device, the device mayfurther comprise a planarization layer formed over at least part of thenon-pixel region of the first substrate, wherein the frit seal does notcontact the planarization layer. The device may further comprise anorganic planarization layer formed over at least part of the non-pixelregion of the first substrate, wherein the organic planarization layercomprises a recess exposing the electrically conductive line. The devicemay further comprise a plurality of thin film transistors interposedbetween the first substrate and the array, wherein the electricallyconductive line is made of a material used in the plurality of thin filmtransistors.

Another aspect of the invention provides a method of making an organiclight emitting device. The method includes providing an unfinisheddevice comprising a first substrate, an array of organic light emittingpixels formed over the first substrate, and an electrically conductiveline formed over the first substrate and not overlapping the array,further providing a second substrate, and interposing a frit between thefirst and second substrates such that the array is interposed betweenthe first and second substrates, that the frit surrounds the array andthat a portion of the electrically conductive line overlaps the frit ina segment of the device, whereby the portion of the electricallyconductive line substantially eclipses the frit in the segment. Themethod further includes melting and resolidifying at least part of thefrit so as to interconnect the unfinished device and the secondsubstrate via the frit, wherein the frit connects to the electricallyconductive line with or without a material therebetween, and wherein thefrit connects to the second substrate with or without a materialtherebetween.

In the above described method, interposing may comprise contacting thefrit with the portion of the electrically conductive line and the secondsubstrate. The unfinished device may further comprise a planarizationlayer generally formed over the electrically conductive line with anopening exposing part of the conductive line, and wherein interposingthe frit comprises contacting the frit with the electrically conductiveline through the opening. Providing the unfinished device may furthercomprise providing the planarization layer over the electricallyconductive line, and selectively etching the planarization layer to formthe opening. The melting may comprise irradiating a laser beam orinfrared ray to at least part of the frit. The interposing of the fritmay comprise forming the frit over at least one of the first and secondsubstrates, and arranging the first and second substrate so as tointerpose the frit therebetween. Forming the frit may comprisescreen-printing or dispensing a material of the frit over at least oneof the first and second substrates. The unfinished device may furthercomprise one or more additional arrays of organic light emitting pixelsand one or more additional electrically conductive lines formed over thefirst substrate.

Still referring to the above described method, the method may furtherinclude forming one or more additional frits between the first andsecond substrates such that each additional frit surrounds one of theadditional arrays and contacts a portion of one of the additionalelectrically conductive lines. The one of the additional electricallyconductive lines may substantially eclipse the additional frit. Themethod may further include cutting the resulting product including theadditional arrays into two or more pieces, where one of the piecescomprises the frit and the array interposed between the first and secondsubstrate.

BRIEF DESCRIPTION OF THE DRAWINGS

The above and other features of the present invention will be describedin reference to certain exemplary embodiments thereof with reference tothe attached drawings in which:

FIG. 1 is a cross-sectional view of an organic light emitting displayaccording to an embodiment;

FIGS. 2 to 5 are cross-sectional views of an organic light emittingdisplay in accordance with an embodiment;

FIG. 6 is a cross-sectional view of an organic light emitting display inaccordance with another embodiment;

FIG. 7A is a schematic exploded view of a passive matrix type organiclight emitting display device in accordance with one embodiment.

FIG. 7B is a schematic exploded view of an active matrix type organiclight emitting display device in accordance with one embodiment.

FIG. 7C is a schematic top plan view of an organic light emittingdisplay in accordance with one embodiment.

FIG. 7D is a cross-sectional view of the organic light emitting displayof FIG. 7C, taken along the line d-d.

FIG. 7E is a schematic perspective view illustrating mass production oforganic light emitting devices in accordance with one embodiment.

DETAILED DESCRIPTION OF CERTAIN INVENTIVE EMBODIMENTS

The present invention will now be described more fully hereinafter withreference to the accompanying drawings, in which some embodiments of theinvention are shown. This invention may, however, be embodied indifferent forms and should not be construed as limited to theembodiments set forth herein. Rather, these embodiments are provided sothat this disclosure will be thorough and complete, and will fullyconvey the scope of the invention to those skilled in the art. In thedrawings, the thickness of layers and regions may be exaggerated forclarity. Like reference numerals designate like elements throughout thespecification.

An organic light emitting display (OLED) is a display device comprisingan array of organic light emitting diodes. Organic light emitting diodesare solid state devices which include an organic material and areadapted to generate and emit light when appropriate electricalpotentials are applied.

OLEDs can be generally grouped into two basic types dependent on thearrangement with which the stimulating electrical current is provided.FIG. 7A schematically illustrates an exploded view of a simplifiedstructure of a passive matrix type OLED 1000. FIG. 7B schematicallyillustrates a simplified structure of an active matrix type OLED 1001.In both configurations, the OLED 1000, 1001 includes OLED pixels builtover a substrate 1002, and the OLED pixels include an anode 1004, acathode 1006 and an organic layer 1010. When an appropriate electricalcurrent is applied to the anode 1004, electric current flows through thepixels and visible light is emitted from the organic layer.

Referring to FIG. 7A, the passive matrix OLED (PMOLED) design includeselongate strips of anode 1004 arranged generally perpendicular toelongate strips of cathode 1006 with organic layers interposedtherebetween. The intersections of the strips of cathode 1006 and anode1004 define individual OLED pixels where light is generated and emittedupon appropriate excitation of the corresponding strips of anode 1004and cathode 1006. PMOLEDs provide the advantage of relatively simplefabrication.

Referring to FIG. 7B, the active matrix OLED (AMOLED) includes drivingcircuits 1012 arranged between the substrate 1002 and an array of OLEDpixels. An individual pixel of AMOLEDs is defined between the commoncathode 1006 and an anode 1004, which is electrically isolated fromother anodes. Each driving circuit 1012 is coupled with an anode 1004 ofthe OLED pixels and further coupled with a data line 1016 and a scanline 1018. In embodiments, the scan lines 1018 supply select signalsthat select rows of the driving circuits, and the data lines 1016 supplydata signals for particular driving circuits. The data signals and scansignals stimulate the local driving circuits 1012, which excite theanodes 1004 so as to emit light from their corresponding pixels.

In the illustrated AMOLED, the local driving circuits 1012, the datalines 1016 and scan lines 1018 are buried in a planarization layer 1014,which is interposed between the pixel array and the substrate 1002. Theplanarization layer 1014 provides a planar top surface on which theorganic light emitting pixel array is formed. The planarization layer1014 may be formed of organic or inorganic materials, and formed of twoor more layers although shown as a single layer. The local drivingcircuits 1012 are typically formed with thin film transistors (TFT) andarranged in a grid or array under the OLED pixel array. The localdriving circuits 1012 may be at least partly made of organic materials,including organic TFT.

AMOLEDs have the advantage of fast response time improving theirdesirability for use in displaying data signals. Also, AMOLEDs have theadvantages of consuming less power than passive matrix OLEDs.

Referring to common features of the PMOLED and AMOLED designs, thesubstrate 1002 provides structural support for the OLED pixels andcircuits. In various embodiments, the substrate 1002 can comprise rigidor flexible materials as well as opaque or transparent materials, suchas plastic, glass, and/or foil. As noted above, each OLED pixel or diodeis formed with the anode 1004, cathode 1006 and organic layer 1010interposed therebetween. When an appropriate electrical current isapplied to the anode 1004, the cathode 1006 injects electrons and theanode 1004 injects holes. In certain embodiments, the anode 1004 andcathode 1006 are inverted; i.e., the cathode is formed on the substrate1002 and the anode is opposingly arranged.

Interposed between the cathode 1006 and anode 1004 are one or moreorganic layers. More specifically, at least one emissive or lightemitting layer is interposed between the cathode 1006 and anode 1004.The light emitting layer may comprise one or more light emitting organiccompounds. Typically, the light emitting layer is configured to emitvisible light in a single color such as blue, green, red or white. Inthe illustrated embodiment, one organic layer 1010 is formed between thecathode 1006 and anode 1004 and acts as a light emitting layer.Additional layers, which can be formed between the anode 1004 andcathode 1006, can include a hole transporting layer, a hole injectionlayer, an electron transporting layer and an electron injection layer.

Hole transporting and/or injection layers can be interposed between thelight emitting layer 1010 and the anode 1004. Electron transportingand/or injecting layers can be interposed between the cathode 1006 andthe light emitting layer 1010. The electron injection layer facilitatesinjection of electrons from the cathode 1006 toward the light emittinglayer 1010 by reducing the work function for injecting electrons fromthe cathode 1006. Similarly, the hole injection layer facilitatesinjection of holes from the anode 1004 toward the light emitting layer1010. The hole and electron transporting layers facilitate movement ofthe carriers injected from the respective electrodes toward the lightemitting layer.

In some embodiments, a single layer may serve both electron injectionand transportation functions or both hole injection and transportationfunctions. In some embodiments, one or more of these layers are lacking.In some embodiments, one or more organic layers are doped with one ormore materials that help injection and/or transportation of thecarriers. In embodiments where only one organic layer is formed betweenthe cathode and anode, the organic layer may include not only an organiclight emitting compound but also certain functional materials that helpinjection or transportation of carriers within that layer.

There are numerous organic materials that have been developed for use inthese layers including the light emitting layer. Also, numerous otherorganic materials for use in these layers are being developed. In someembodiments, these organic materials may be macromolecules includingoligomers and polymers. In some embodiments, the organic materials forthese layers may be relatively small molecules. The skilled artisan willbe able to select appropriate materials for each of these layers in viewof the desired functions of the individual layers and the materials forthe neighboring layers in particular designs.

In operation, an electrical circuit provides appropriate potentialbetween the cathode 1006 and anode 1004. This results in an electricalcurrent flowing from the anode 1004 to the cathode 1006 via theinterposed organic layer(s). In one embodiment, the cathode 1006provides electrons to the adjacent organic layer 1010. The anode 1004injects holes to the organic layer 1010. The holes and electronsrecombine in the organic layer 1010 and generate energy particles called“excitons.” The excitons transfer their energy to the organic lightemitting material in the organic layer 1010, and the energy is used toemit visible light from the organic light emitting material. Thespectral characteristics of light generated and emitted by the OLED1000, 1001 depend on the nature and composition of organic molecules inthe organic layer(s). The composition of the one or more organic layerscan be selected to suit the needs of a particular application by one ofordinary skill in the art.

OLED devices can also be categorized based on the direction of the lightemission. In one type referred to as “top emission” type, OLED devicesemit light and display images through the cathode or top electrode 1006.In these embodiments, the cathode 1006 is made of a material transparentor at least partially transparent with respect to visible light. Incertain embodiments, to avoid losing any light that can pass through theanode or bottom electrode 1004, the anode may be made of a materialsubstantially reflective of the visible light. A second type of OLEDdevices emits light through the anode or bottom electrode 1004 and iscalled “bottom emission” type. In the bottom emission type OLED devices,the anode 1004 is made of a material which is at least partiallytransparent with respect to visible light. Often, in bottom emissiontype OLED devices, the cathode 1006 is made of a material substantiallyreflective of the visible light. A third type of OLED devices emitslight in two directions, e.g. through both anode 1004 and cathode 1006.Depending upon the direction(s) of the light emission, the substrate maybe formed of a material which is transparent, opaque or reflective ofvisible light.

In many embodiments, an OLED pixel array 1021 comprising a plurality oforganic light emitting pixels is arranged over a substrate 1002 as shownin FIG. 7C. In embodiments, the pixels in the array 1021 are controlledto be turned on and off by a driving circuit (not shown), and theplurality of the pixels as a whole displays information or image on thearray 1021. In certain embodiments, the OLED pixel array 1021 isarranged with respect to other components, such as drive and controlelectronics to define a display region and a non-display region. Inthese embodiments, the display region refers to the area of thesubstrate 1002 where OLED pixel array 1021 is formed. The non-displayregion refers to the remaining areas of the substrate 1002. Inembodiments, the non-display region can contain logic and/or powersupply circuitry. It will be understood that there will be at leastportions of control/drive circuit elements arranged within the displayregion. For example, in PMOLEDs, conductive components will extend intothe display region to provide appropriate potential to the anode andcathodes. In AMOLEDs, local driving circuits and data/scan lines coupledwith the driving circuits will extend into the display region to driveand control the individual pixels of the AMOLEDs.

One design and fabrication consideration in OLED devices is that certainorganic material layers of OLED devices can suffer damage or accelerateddeterioration from exposure to water, oxygen or other harmful gases.Accordingly, it is generally understood that OLED devices be sealed orencapsulated to inhibit exposure to moisture and oxygen or other harmfulgases found in a manufacturing or operational environment. FIG. 7Dschematically illustrates a cross-section of an encapsulated OLED device1011 having a layout of FIG. 7C and taken along the line d-d of FIG. 7C.In this embodiment, a generally planar top plate or substrate 1061engages with a seal 1071 which further engages with a bottom plate orsubstrate 1002 to enclose or encapsulate the OLED pixel array 1021. Inother embodiments, one or more layers are formed on the top plate 1061or bottom plate 1002, and the seal 1071 is coupled with the bottom ortop substrate 1002, 1061 via such a layer. In the illustratedembodiment, the seal 1071 extends along the periphery of the OLED pixelarray 1021 or the bottom or top plate 1002, 1061.

In embodiments, the seal 1071 is made of a frit material as will befurther discussed below. In various embodiments, the top and bottomplates 1061, 1002 comprise materials such as plastics, glass and/ormetal foils which can provide a barrier to passage of oxygen and/orwater to thereby protect the OLED pixel array 1021 from exposure tothese substances. In embodiments, at least one of the top plate 1061 andthe bottom plate 1002 are formed of a substantially transparentmaterial.

To lengthen the life time of OLED devices 1011, it is generally desiredthat seal 1071 and the top and bottom plates 1061, 1002 provide asubstantially non-permeable seal to oxygen and water vapor and provide asubstantially hermetically enclosed space 1081. In certain applications,it is indicated that the seal 1071 of a frit material in combinationwith the top and bottom plates 1061, 1002 provide a barrier to oxygen ofless than approximately 10⁻³ cc/m²-day and to water of less than 10⁻⁶g/m²-day. Given that some oxygen and moisture can permeate into theenclosed space 1081, in some embodiments, a material that can take upoxygen and/or moisture is formed within the enclosed space 1081.

The seal 1071 has a width W, which is its thickness in a directionparallel to a surface of the top or bottom substrate 1061, 1002 as shownin FIG. 7D. The width varies among embodiments and ranges from about 300μm to about 3000 μm, optionally from about 500 μm to about 1500 μm.Also, the width may vary at different positions of the seal 1071. Insome embodiments, the width of the seal 1071 may be the largest wherethe seal 1071 contacts one of the bottom and top substrate 1002, 1061 ora layer formed thereon. The width may be the smallest where the seal1071 contacts the other. The width variation in a single cross-sectionof the seal 1071 relates to the cross-sectional shape of the seal 1071and other design parameters.

The seal 1071 has a height H, which is its thickness in a directionperpendicular to a surface of the top or bottom substrate 1061, 1002 asshown in FIG. 7D. The height varies among embodiments and ranges fromabout 2 μm to about 30 μm, optionally from about 10 μm to about 15 μm.Generally, the height does not significantly vary at different positionsof the seal 1071. However, in certain embodiments, the height of theseal 1071 may vary at different positions thereof.

In the illustrated embodiment, the seal 1071 has a generally rectangularcross-section. In other embodiments, however, the seal 1071 can haveother various cross-sectional shapes such as a generally squarecross-section, a generally trapezoidal cross-section, a cross-sectionwith one or more rounded edges, or other configuration as indicated bythe needs of a given application. To improve hermeticity, it isgenerally desired to increase the interfacial area where the seal 1071directly contacts the bottom or top substrate 1002, 1061 or a layerformed thereon. In some embodiments, the shape of the seal can bedesigned such that the interfacial area can be increased.

The seal 1071 can be arranged immediately adjacent the OLED array 1021,and in other embodiments, the seal 1071 is spaced some distance from theOLED array 1021. In certain embodiment, the seal 1071 comprisesgenerally linear segments that are connected together to surround theOLED array 1021. Such linear segments of the seal 1071 can extend, incertain embodiments, generally parallel to respective boundaries of theOLED array 1021. In other embodiment, one or more of the linear segmentsof the seal 1071 are arranged in a non-parallel relationship withrespective boundaries of the OLED array 1021. In yet other embodiments,at least part of the seal 1071 extends between the top plate 1061 andbottom plate 1002 in a curvilinear manner.

As noted above, in certain embodiments, the seal 1071 is formed using afrit material or simply “frit” or glass frit,” which includes fine glassparticles. The frit particles includes one or more of magnesium oxide(MgO), calcium oxide (CaO), barium oxide (BaO), lithium oxide (Li₂O),sodium oxide (Na₂O), potassium oxide (K₂O), boron oxide (B₂O₃), vanadiumoxide (V₂O₅), zinc oxide (ZnO), tellurium oxide (TeO₂), aluminum oxide(Al₂O₃), silicon dioxide (SiO₂), lead oxide (PbO), tin oxide (SnO),phosphorous oxide (P₂O₅), ruthenium oxide (Ru₂O), rubidium oxide (Rb₂O),rhodium oxide (Rh₂O), ferrite oxide (Fe₂O₃), copper oxide (CuO),titanium oxide (TiO₂), tungsten oxide (WO₃), bismuth oxide (Bi₂O₃),antimony oxide (Sb₂O₃), lead-borate glass, tin-phosphate glass, vanadateglass, and borosilicate, etc. In embodiments, these particles range insize from about 2 μm to about 30 μm, optionally about 5 μm to about 10μm, although not limited only thereto. The particles can be as large asabout the distance between the top and bottom substrates 1061, 1002 orany layers formed on these substrates where the frit seal 1071 contacts.

The frit material used to form the seal 1071 can also include one ormore filler or additive materials. The filler or additive materials canbe provided to adjust an overall thermal expansion characteristic of theseal 1071 and/or to adjust the absorption characteristics of the seal1071 for selected frequencies of incident radiant energy. The filler oradditive material(s) can also include inversion and/or additive fillersto adjust a coefficient of thermal expansion of the frit. For example,the filler or additive materials can include transition metals, such aschromium (Cr), iron (Fe), manganese (Mn), cobalt (Co), copper (Cu),and/or vanadium. Additional materials for the filler or additivesinclude ZnSiO₄, PbTiO₃, ZrO₂, eucryptite.

In embodiments, a frit material as a dry composition contains glassparticles from about 20 to 90 about wt %, and the remaining includesfillers and/or additives. In some embodiments, the frit paste containsabout 10-30 wt % organic materials and about 70-90% inorganic materials.In some embodiments, the frit paste contains about 20 wt % organicmaterials and about 80 wt % inorganic materials. In some embodiments,the organic materials may include about 0-30 wt % binder(s) and about70-100 wt % solvent(s). In some embodiments, about 10 wt % is binder(s)and about 90 wt % is solvent(s) among the organic materials. In someembodiments, the inorganic materials may include about 0-10 wt %additives, about 20-40 wt % fillers and about 50-80 wt % glass powder.In some embodiments, about 0-5 wt % is additive(s), about 25-30 wt % isfiller(s) and about 65-75 wt % is the glass powder among the inorganicmaterials.

In forming a frit seal, a liquid material is added to the dry fritmaterial to form a frit paste. Any organic or inorganic solvent with orwithout additives can be used as the liquid material. In embodiments,the solvent includes one or more organic compounds. For example,applicable organic compounds are ethyl cellulose, nitro cellulose,hydroxyl propyl cellulose, butyl carbitol acetate, terpineol, butylcellusolve, acrylate compounds. Then, the thus formed frit paste can beapplied to form a shape of the seal 1071 on the top and/or bottom plate1061, 1002.

In one exemplary embodiment, a shape of the seal 1071 is initiallyformed from the frit paste and interposed between the top plate 1061 andthe bottom plate 1002. The seal 1071 can in certain embodiments bepre-cured or pre-sintered to one of the top plate and bottom plate 1061,1002. Following assembly of the top plate 1061 and the bottom plate 1002with the seal 1071 interposed therebetween, portions of the seal 1071are selectively heated such that the frit material forming the seal 1071at least partially melts. The seal 1071 is then allowed to resolidify toform a secure joint between the top plate 1061 and the bottom plate 1002to thereby inhibit exposure of the enclosed OLED pixel array 1021 tooxygen or water.

In embodiments, the selective heating of the frit seal is carried out byirradiation of light, such as a laser or directed infrared lamp. Aspreviously noted, the frit material forming the seal 1071 can becombined with one or more additives or filler such as species selectedfor improved absorption of the irradiated light to facilitate heatingand melting of the frit material to form the seal 1071.

In some embodiments, OLED devices 1011 are mass produced. In anembodiment illustrated in FIG. 7E, a plurality of separate OLED arrays1021 is formed on a common bottom substrate 1101. In the illustratedembodiment, each OLED array 1021 is surrounded by a shaped frit to formthe seal 1071. In embodiments, common top substrate (not shown) isplaced over the common bottom substrate 1101 and the structures formedthereon such that the OLED arrays 1021 and the shaped frit paste areinterposed between the common bottom substrate 1101 and the common topsubstrate. The OLED arrays 1021 are encapsulated and sealed, such as viathe previously described enclosure process for a single OLED displaydevice. The resulting product includes a plurality of OLED devices kepttogether by the common bottom and top substrates. Then, the resultingproduct is cut into a plurality of pieces, each of which constitutes anOLED device 1011 of FIG. 7D. In certain embodiments, the individual OLEDdevices 1011 then further undergo additional packaging operations tofurther improve the sealing formed by the frit seal 1071 and the top andbottom substrates 1061, 1002.

FIG. 1 is a cross-sectional view of an organic light emitting displayaccording to an embodiment. Referring to FIG. 1, the organic lightemitting display includes a semiconductor layer 110, a gate insulatinglayer 120, a gate electrode 130 a, a scan driver 130 b, an interlayerinsulating layer 140, and source and drain electrodes 150, which aredisposed on a substrate 100 having a pixel region I and a non-pixelregion II. In addition, the organic light emitting display furtherincludes a common power supply line 150 b, and a second electrode powersupply line 150 a, which are formed of source and draininterconnections.

A planarization layer 160 is disposed on the entire surface of thesubstrate 100. The planarization layer 160 is formed of an organicmaterial such as acryl-based resin or polyimide-based resin. Theplanarization layer 160 has via-holes for exposing the common powersupply line 150 b, the second electrode power supply line 150 a, and thesource and/or drain electrodes 150. The common power supply line 150 bis partially exposed to enhance adhesive strength when the substrate issealed using a glass frit.

A first electrode 171 including a reflective layer 170 is disposed onthe substrate 100, and a pixel defining layer 180 is disposed on theentire surface of the substrate 100. An organic layer 190 including atleast an emission layer is disposed on the first electrode 171, and asecond electrode 200 is disposed thereon. An encapsulation substrate 210is disposed opposite to the substrate 100, and the substrate 100 and theencapsulation substrate 210 are sealed with a glass frit 220, therebyforming an organic light emitting display.

However, in the foregoing embodiment, the organic light emitting displayincludes an organic planarization layer disposed under the glass fritfor sealing the substrate so that the organic planarization layer may bedamaged due to a large amount of heat generated when a laser beam isradiated to the glass frit. As a result, adhesive strength at aninterface in which the glass frit is adhered to the organicplanarization layer may be lowered.

FIGS. 2 to 5 are cross-sectional views of an organic light emittingdisplay in accordance with another embodiment. Referring to FIG. 2, asubstrate 300 including a pixel region I, and a non-pixel region II isprovided. The substrate 300 may be an insulating glass substrate, aplastic substrate, or a conductive substrate.

A buffer layer 310 is formed on the surface of the substrate 300. Thebuffer layer 310 may be a silicon oxide layer, a silicon nitride layer,or a composite layer of silicon oxide and silicon nitride. In oneaspect, the buffer layer 310 functions as a passivation layer forpreventing impurities from out-diffusing from the substrate 300.

A semiconductor layer 320 is formed on the buffer layer 310 in the pixelregion I. The semiconductor layer 320 may be an amorphous silicon layeror a polysilicon layer. A gate insulating layer 330 is formed on thesurface of the substrate 300 and the semiconductor layer 320. The gateinsulating layer 330 may be a silicon oxide layer, a silicon nitridelayer, or a composite layer of silicon oxide and silicon nitride.

After forming the gate insulating layer 330, a gate electrode 340 a isformed on the gate insulating layer 330 located above a portion of thesemiconductor layer 320. The gate electrode 340 a may be comprised ofAl, Cu, and/or Cr.

An interlayer insulating layer 350 is formed on the surface of thesubstrate 300 and the gate electrode 340 a. The interlayer insulatinglayer 350 may be a silicon oxide layer, a silicon nitride layer, or acomposite layer of silicon oxide and silicon nitride.

The interlayer insulating layer 350 and the gate insulating layer 330 inthe pixel region I are then etched to form contact holes 351 and 352 forexposing the semiconductor layer 320. Source and drain electrodes 360 aand 360 b are formed on the interlayer insulating layer 350 in the pixelregion I connecting to the semiconductor layer 320 through the contactholes 351 and 352. The source and drain electrodes 360 a and 360 b maybe formed of one or more materials including, for example, Mo, Cr, Al,Ti, Au, Pd and Ag.

Further, at the same time the source and drain electrodes 360 a and 360b are formed, the electrically conductive line 360 d is formed in thenon-pixel region II. The electrically conductive line 360 d may act as acommon power supply line. In addition, a second electrode power supplyline 360 c may also be formed at the same time. Furthermore, at the sametime the gate electrode 340 a is formed, a scan driver line 340 b may beformed in the non-pixel region II.

While a top gate thin film transistor configuration is described in thisembodiment, a bottom gate thin film transistor having a gate electrodedisposed under a semiconductor layer may also be formed. In addition,while the electrically conductive line, in this embodiment, is formed atthe same time the source and drain electrodes are formed, theelectrically conductive line may also be formed at the same time thegate electrode or the first electrode is formed.

Referring to FIG. 3, an organic planarization layer 370 is formed on thesurface of the substrate 300. The organic planarization layer 370 may beformed using an organic material such as acryl-based resin,polyimide-based resin, or benzocyclobutene (BCB). The organicplanarization layer 370 is then etched to form via-holes 371 a and 371 bfor exposing at least one of the source and/or drain electrodes 360 aand 360 b in the pixel region I, and the second electrode power supplyline 360 c in the non-pixel region II.

In addition, the organic planarization layer 370 in the non-pixel regionII, where the electrically conductive line 360 d is located, is removedby etching to form a recess exposing the electrically conductive line360 d. When the substrate is sealed using a glass frit, the glass fritis irradiated with a laser beam to adhere the substrates. At this time,if the organic planarization layer still existed under the glass frit,the planarization layer may be damaged due to a large amount of heatgenerated from the laser. As a result, the glass frit may be delaminatedfrom an interface with the planarization layer to decrease adhesivestrength thereof. Therefore, the organic planarization layer at the edgeof the substrate 300, to which the glass frit is to be adhered, isremoved to prevent the above problems.

Referring to FIG. 4, a first electrode 380 including a reflective layer375 is formed on the organic planarization layer 370 in the pixel regionI. The first electrode 380 is disposed on a bottom surface of thevia-hole 371 to be in contact with one of the exposed source and/ordrain electrodes 360 a and 360 b, and extends onto the organicplanarization layer 370. The first electrode 380 may be formed of indiumtin oxide (ITO) or indium zinc oxide (IZO).

After forming the first electrode 380, a pixel defining layer 390 isformed on the surface of the substrate 300 including at least the firstelectrode 380. The pixel defining layer is formed to a thicknesssufficient to fill the via-hole 371 a, in which the first electrode 380is disposed. The pixel defining layer 390 may be formed of an organiclayer or an inorganic layer, preferably, an organic layer. Morepreferably, the pixel defining layer 390 is formed of one selected fromthe group including BCB, acryl-based polymer, and polyimide. Thematerial comprising the pixel defining layer 390 preferably has highflowability such that the pixel defining layer can be evenly formed onthe entire surface of the substrate.

At this time, the pixel defining layer 390 is etched to form openings395 a for exposing the first electrode 380 in the pixel region I, and aportion of the second electrode power supply line 360 c in the non-pixelregion II. In addition, the pixel defining layer 390 in the non-pixelregion II, at which the electrically conductive line 360 d is disposed,is also removed by etching.

After forming the pixel defining layer 390 and etching the opening 395a, an organic layer 400 is formed on the first electrode 380 exposedthrough the opening 395 a. The organic layer 400 includes at least anemission layer, and may further include at least one of a hole injectionlayer, a hole transport layer, an electron transport layer, and anelectron injection layer.

Next, a second electrode 410 is formed on the surface of the substrate300. The second electrode 410 is a transmissive electrode, and may beformed of Mg, Ag, Al, Ca, or an alloy thereof, which is transparent andhas a low work function. At this time, the second electrode 410 isetched to expose the electrically conductive line 360 d in the non-pixelregion II.

Referring to FIG. 5, an encapsulation substrate 420 opposite to thesubstrate 300 is provided. The encapsulation substrate 420 may be formedof an etched insulating glass or a non-etched insulating glass.

In one embodiment, a glass frit 430 is applied to the edge of theencapsulation substrate 420 opposite to the substrate 300. The glassfrit 430 may be formed of material selected from the group consisting ofmagnesium oxide (MgO), calcium oxide (CaO), barium oxide (BaO), lithiumoxide (Li₂O), sodium oxide (Na₂O), potassium oxide (K₂O), boron oxide(B₂)₃), vanadium oxide (V₂O₅), zinc oxide (ZnO), tellurium oxide (TeO₂),aluminum oxide (Al₂O₃), silicon dioxide (SiO₂), lead oxide (PbO), tinoxide (SnO), phosphorous oxide (P₂O₅), ruthenium oxide (Ru₂O), rubidiumoxide (Rb₂O), rhodium oxide (Rh₂O), ferrite oxide (Fe₂O₃), copper oxide(CuO), titanium oxide (TiO₂), tungsten oxide (WO₃), bismuth oxide(Bi₂O₃), antimony oxide (Sb₂O₃), lead-borate glass, tin-phosphate glass,vanadate glass, and borosilicate, and a composite thereof. The glassfrit 430 may be applied by a dispensing method or a screen printingmethod.

In the example shown in FIG. 5, the glass frit 430 has a width largerthan that of the electrically conductive line 360 d. As the glass frit430 has a larger width, the adhesive strength increases. Therefore, itis possible to protect an element from external moisture or oxygen. Inthis embodiment, the glass frit 430 is applied on the encapsulatingsubstrate 420. In other embodiments, the glass frit 430 may be appliedon the substrate 300, or on both the substrate 300 and the encapsulationsubstrate 420.

After applying the glass frit 430, the substrate 300 and theencapsulation substrate 420 are aligned and adhered to each other. Atthis time, the glass frit 430 is in contact with the electricallyconductive line 360 d and the interlayer insulating layer 350 on thesubstrate 300.

After contacting the substrate 300 with the encapsulation substrate 420via the glass frit 430, the glass frit 430 is irradiated with a laserbeam. The glass frit 430 is melted and solidified to adhere thesubstrate 300 and the encapsulation substrate 420, thereby completingthe organic light emitting display of an embodiment.

It should be noted, that while the example described above in referenceto FIGS. 2-5 showed a single organic light emitting pixel beingencapsulated, similar procedures may be used to encapsulate an array oforganic light emitting pixels. Additionally, multiple arrays of organiclight emitting pixels may be encapsulated between a single substrate 300and a single encapsulation substrate 420 and be surrounded by additionalglass frits 430 (e.g., in a mass production configuration). The multiplearrays may be cut apart resulting in individual arrays encapsulated bythe substrate 300, the encapsulation substrate 420 and a glass frit 430.

As described above, if the organic planarization layer is disposed underthe glass frit for sealing the substrate, the organic planarizationlayer may be damaged due to the large amount of heat generated when thelaser beam is radiated to the glass frit. As a result, the glass fritmay be delaminated from an interface with the planarization layer todecrease adhesive strength thereof. On the other hand, the organicplanarization layer in the area of the glass frit may be removed toprevent adhesive strength of the glass frit from being lowered.

FIG. 6 is a cross-sectional view of an organic light emitting display inaccordance with another embodiment of the present invention. Referringto FIG. 6, the organic light emitting display is formed in a mannersimilar to the embodiment discussed above in reference to FIGS. 2-5,where a glass frit 630 is applied on an encapsulating substrate 620, anda substrate 500 is adhered to the encapsulating substrate 620. The glassfrit 630 is then irradiated with a laser beam such that the glass frit630 is melted and solidified, thereby completing the organic lightemitting display.

In this embodiment, the glass frit 630 has a width equal to or smallerthan that of the electrically conductive line 560 d. In the embodimentshown in FIG. 5, the glass frit 430 was wider than the electricallyconductive line 560 d. In one aspect of this embodiment, theelectrically conductive line 560 d substantially eclipses or totallyeclipses the glass frit 630 as viewed from the substrate 300. While thewider glass frit 430 may provide increased adhesive strength compared tothe glass frit 630, a narrower glass frit such as the glass frit 630 maybe sufficient, depending on the embodiment. In addition, since anorganic planarization layer does not exist under the glass frit (eitherthe glass frit 430 or the glass frit 630), it is possible to prevent theadhesive strength of either of the glass frits 430 or 630 from beinglowered.

In this embodiment, the glass frit 630 is applied on the encapsulatingsubstrate 620. In other embodiments, the glass frit 430 may be appliedon the substrate 500, or on both the substrate 500 and the encapsulatingsubstrate 620.

As described above, in the embodiment where the organic planarizationlayer is disposed under the glass frit for sealing the substrate so thatthe organic planarization layer may be damaged due to the large amountof heat generated when the laser beam is radiated to the glass frit. Asa result, the glass frit may be delaminated from an interface with theplanarization layer to decrease adhesive strength thereof. However, inother embodiments, the organic planarization layer under the glass fritis removed to prevent adhesive strength of the glass frit from beinglowered. Therefore, it is possible to prevent intrusion of externalmoisture or oxygen to improve reliability of an element.

While the foregoing embodiments of the present invention exemplarilydescribe the electrically conductive line positioned at both sides ofthe substrate and disposed under the glass frit, the electricallyconductive line may be disposed on and under the substrate and under theglass frit.

As can be seen from the foregoing, an organic light emitting display anda method of fabricating the same in accordance with the presentinvention can prevent adhesive strength of a glass frit from beinglowered when a substrate is sealed using the glass frit, therebyimproving reliability.

Although the present invention has been described with reference tocertain exemplary embodiments thereof, it will be understood by thoseskilled in the art that a variety of modifications and variations may bemade to the present invention without departing from the spirit or scopeof the present invention defined in the appended claims, and theirequivalents.

1. An organic light emitting device comprising: a first substratecomprising a pixel region and a non-pixel region; an array of organiclight emitting pixels formed over the pixel region of the firstsubstrate; a second substrate placed over the first substrate, the arraybeing interposed between the first and second substrates; anelectrically conductive line formed over the non-pixel region of thefirst substrate; and a frit seal interposed between the first and secondsubstrates and surrounding the array such that the array is encapsulatedby the first substrate, the second substrate and the frit seal, whereinthe electrically conductive line comprises a portion overlapping thefrit seal in a segment of the device such that the portion of theelectrically conductive line substantially eclipses the frit seal whenviewed from the first substrate.
 2. The device of claim 1, wherein theportion of the electrically conductive line substantially totallyeclipses the frit seal when viewed from the first substrate.
 3. Thedevice of claim 1, wherein the frit seal contacts the electricallyconductive line.
 4. The device of claim 1, wherein there issubstantially no material between the frit seal and the electricallyconductive line.
 5. The device of claim 1, wherein the device furthercomprises at least one layer located between the electrically conductiveline and the first substrate, the at least one layer comprising anorganic material.
 6. The device of claim 1, wherein the electricallyconductive line further comprises a portion that does not overlap thefrit seal.
 7. The device of claim 1, wherein the electrically conductiveline extends along a peripheral edge of the first substrate, and whereinthe frit seal extends along the peripheral edge of the first edge. 8.The device of claim 1, wherein the electrically conductive line is madeof metal.
 9. The device of claim 1, wherein in another segment of thedevice, the frit seal further comprises a non-eclipsed portion that isnot eclipsed by the electrically conductive line when viewed from thefirst substrate.
 10. The device of claim 1, wherein the frit seal has awidth taken in a cross-sectional plane, and the electrically conductiveline has a width taken in the cross-sectional plane, and wherein thewidth of the frit seal is substantially smaller than the width of theelectrically conductive line.
 11. The device of claim 1, wherein theelectrically conductive line comprises a power supply line electricallyconnected to the array.
 12. The device of claim 1, wherein theelectrically conductive line comprises a portion overlapping the fritseal in substantially throughout the device such that the portion of theelectrically conductive line substantially eclipses the frit seal whenviewed from the first substrate.
 13. The device of claim 1, furthercomprising a planarization layer formed over at least part of thenon-pixel region of the first substrate, wherein the frit seal does notcontact the planarization layer.
 14. The device of claim 1, furthercomprising an organic or inorganic planarization layer formed over atleast part of the non-pixel region of the first substrate, wherein theorganic planarization layer comprises a recess exposing the electricallyconductive line.
 15. The device of claim 1, further comprising aplurality of thin film transistors interposed between the firstsubstrate and the array, wherein the electrically conductive line ismade of a material used in the plurality of thin film transistors. 16.The device of claim 1, wherein the frit seal comprises one or morematerials selected from the group consisting of magnesium oxide (MgO),calcium oxide (CaO), barium oxide (BaO), lithium oxide (Li₂O), sodiumoxide (Na₂O), potassium oxide (K₂O), boron oxide (B₂O₃), vanadium oxide(V₂O₅), zinc oxide (ZnO), tellurium oxide (TeO₂), aluminum oxide(Al₂O₃), silicon dioxide (SiO₂), lead oxide (PbO), tin oxide (SnO),phosphorous oxide (P₂O₅), ruthenium oxide (Ru₂O), rubidium oxide (Rb₂O),rhodium oxide (Rh₂O), ferrite oxide (Fe₂O₃), copper oxide (CuO),titanium oxide (TiO₂), tungsten oxide (WO₃), bismuth oxide (Bi₂O₃),antimony oxide (Sb₂O₃), lead-borate glass, tin-phosphate glass, vanadateglass, and borosilicate.
 17. An organic light emitting devicecomprising: a first substrate comprising a pixel region and a non-pixelregion; an array of organic light emitting pixels formed over the pixelregion of the first substrate; a second substrate placed over the firstsubstrate, the array being interposed between the first and secondsubstrates; a frit seal interposed between the first and secondsubstrates and surrounding the array such that the array is encapsulatedby the first substrate, the second substrate and the frit seal; and aplanarization layer formed over the first substrate, wherein the fritseal does not contact the planarization layer.
 18. The device of claim17, wherein the planarization layer comprises a recess, and wherein atleast part of the frit seal extends into the recess.
 19. The device ofclaim 17, wherein the planarization layer extends over at least part ofthe pixel region and at least part of the non-pixel region.
 20. Thedevice of claim 17, wherein the planarization layer comprises an organicmaterial.
 21. The device of claim 17, wherein the planarization layercomprises an inorganic material.
 22. The device of claim 17, furthercomprising an electrically conductive line formed over the non-pixelregion of the first substrate, wherein the electrically conductive linecomprises a portion overlapping the frit seal in a segment of the devicesuch that the portion of the electrically conductive line substantiallyeclipses the frit seal when viewed from the first substrate.
 23. Thedevice of claim 22, wherein the planarization layer does not contact theoverlapping portion of the electrically conductive line.
 24. A method ofmaking an organic light emitting device, the method comprising:providing an unfinished device comprising a first substrate, an array oforganic light emitting pixels formed over the first substrate, and anelectrically conductive line formed over the first substrate and notoverlapping the array; further providing a second substrate; interposinga frit between the first and second substrates such that the array isinterposed between the first and second substrates, that the fritsurrounds the array and that a portion of the electrically conductiveline overlaps the frit in a segment of the device, whereby the portionof the electrically conductive line substantially eclipses the frit inthe segment; and melting and resolidifying at least part of the frit soas to interconnect the unfinished device and the second substrate viathe frit, wherein the frit connects to the electrically conductive linewith or without a material therebetween, and wherein the frit connectsto the second substrate with or without a material therebetween.
 25. Themethod of claim 24, wherein interposing comprises contacting the fritwith the portion of the electrically conductive line and the secondsubstrate.
 26. The method of claim 24, wherein the unfinished devicefurther comprises a planarization layer generally formed over theelectrically conductive line with an opening exposing part of theconductive line, and wherein interposing the frit comprises contactingthe frit with the electrically conductive line through the opening. 27.The method of claim 26, wherein providing the unfinished devicecomprises: providing the planarization layer over the electricallyconductive line; and selectively etching the planarization layer to formthe opening.
 28. The method of claim 24, wherein the melting comprisesirradiating a laser beam or infrared ray to at least part of the frit.29. The method of claim 24, wherein interposing the frit comprises:forming the frit over at least one of the first and second substrates;and arranging the first and second substrate so as to interpose the frittherebetween.
 30. The method of claim 29, wherein forming the fritcomprises screen-printing or dispensing a material of the frit over atleast one of the first and second substrates.
 31. The method of claim24, wherein the unfinished device further comprises one or moreadditional arrays of organic light emitting pixels and one or moreadditional electrically conductive lines formed over the firstsubstrate; wherein the method further comprises forming one or moreadditional frits between the first and second substrates such that eachadditional frit surrounds one of the additional arrays and contacts aportion of one of the additional electrically conductive lines.
 32. Themethod of claim 31, wherein the one of the additional electricallyconductive lines substantially eclipses the additional frit.
 33. Themethod of claim 31, further comprising cutting the resulting product ofclaim 31 into two or more pieces, wherein one of the pieces comprisesthe frit and the array interposed between the first and secondsubstrate.